Nitrogen (N) may be easily leached from a sand-based system. Frequent application of N is a way to reduce leaching. Repeated applications result in increasing cost. Slow-release fertilizers were designed to provide a steady release of N over time. Use of slow-release N sources has been promoted as a more efficient N fertilizer strategy. This study was conducted to evaluate N leaching, root and shoot growth, and nitrogen use efficiency (NUE) when urea and methylene urea were placed at four mixing depths in a sand-based system. Grass clipping samples were collected every two weeks, dried and weighed. Root dry weight and root organic matter were evaluated at the end of the study. Leachate was collected weekly and analyzed for nitrate-nitrogen (NO3-N) content. Surface applied urea produced the largest clipping yield and the best NUE for total mass yield, with the lowest NO3-N loss due to leaching. When applied subsurface, Methylene urea at the deepest mixing depth of 22.9 cm produced 121% more shoot growth, 57% less NO3-N leaching, and 46% more NUE for total mass than urea. Split applications of surface applied urea provided the best establishment of Kentucky bluegrass sod on sand-based systems based on the results of the study.
Figures & Tables
Fig. 1. Mean clipping dry weight (g m) per unit surface area of ‘Unique’ Poa pratensis L. by N source and N rate. Each mean was averaged from 32 observations (four replications × four mixing depth levels × two years). The vertical bar represents the standard error of difference (SED).